Drilling bit



Sept. 12, 1944. I L. R. LEISSLER- 2,357,335

DRILLING BIT Filed Jill 20, 1942 2 Sheets-Sheet 1 LEE RLussLm INVENTOR.

BY mfi0=-k p 1944. R. LEISSLER 2,357,835

DRILLING BIT Filed 'July 20, 1942 2 Sheets-Sheet 2 LEE RLEISSLER INVENTOR.

d wn 6mm HTTO/P/VEY Patented Sept. 12, 1944 2,357,835 DRILLING BIT Lee R; Leissler, Houston, Tex., assignor to Carl C. Cawthon and Lee R. Leissler, a partnership Application July 20, 1942, Serial No. 452,680

13 Claims.

The invention relates to what is generally known as a drag bit used in the rotary method of drilling wells but is of a peculiar configuration to obtain a slicing action on the formation being drilled so as to slice off thin layers of the material which can be readily broken up by the circulation of the flushing fluid so that they will be carried away from the cutting edge promptly and will not tend to settle from the column of drilling fluid rising in the well.

In the drilling of wells with a drag bit, the formation being drilled is usually soft or only medium hard and it is the intention to rotate the bit at a relatively high speed and to advance it as quickly as possible so as to make the maximum amount of hole. Where the hole is being drilled at a high rate, naturally the cuttings must be carried away from the bit promptly and must be in rather finely divided form so that they will not settle from the column of mud.

With this in mind the present bit has been devised to rotate at a relatively high speed so as to cut thin slices of the material from the formation and to break up these cuttings into fine particles and to carry them away from the cutting edges as quickly as possible.

It is therefore one of the objects of the invention to provide a drag bit with a slicing type of cutting blade.

Another object of the invention is to provide a drag bit with blades wherein a sliding, slicing action is accomplished due to the peculiar configuration of the cutting'edge.

Another object of the invention is to provide an inclined cutting edge for a bit blade so that a greater length of cutting edge will be in contact with the formation to extend the life or service obtainable with the bit. 1

Another object of the invention is to provide a round nosed slicing type of bit wherein the blades incline downwardly, rearwardly and inwardly.

Another object of the invention is to provide a series of claw-like blades for a drag bit so as to provide a central chamber in which the cuttings will be whipped into fine particles by the circulation of the drilling fluid.

Still another object of the invention is to provide a multiple blade drag bit wherein the blades are so curved and inclined that flushing fluid discharging from the rear of one blade impinges upon the cutting face of the next following blade so as to wash the cuttings therefrom.

' Still another object of the invention is to'provide a cutting blade for drag bits which is substantially triangular in cross section with a water course discharging from the rear edge of the blade.

Still another object of the invention is to provide a drag bit with claw like blades wherein a washing fluid is discharged from each blade and also into the area encompassed by the blades.

Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accom panying drawings wherein:

Fig. 1 is a side elevation of a two-bladed bit embodying the invention and illustrating the manner of arrangement of the blades,

Fig. 2 is an edge elevation looking at the bit at right angles as compared with Fig. 1.

Fig. 3 is a bottom plan view looking into the blades.

Fig. 4 is a side elevation of a three-bladed bit and illustrating the general arrangement and assembly of the blades.

Fig. 5 is a section taken on the line 5-5 of Fig. 4 and illustrating the tringular configuration of the blades in cross section.

Fig. 6 is a section taken on the line 66 of Fig. 5 and illustrating the internal construction and arrangement of the blades.

The bit includes a body I having a threaded connection 2 thereon which may be in the, form of a pin as seen in Figs. 1 and 2, or it may be in the form of an internal box, as seen in Fig. 6. In either event the central portion of the body I is hollow to form an enlarged recess 3 which is to receive the flow of flushing or drilling fluid which is circulated down thru the drill stem to. which the bit will be connected. I

Particular attention is directed to the peculiar formation of the claw-like blades 5 and 6, two of which are seen in Fig. 1. These blades extend downwardly from the body I and as seen in Fig. 2, have a forward slicing edge 1 which extends inwardly to provide the cutting face 8. The blade is thickened as it extends rearwardly from the slicing edge 1 and this slicing edge extends downwardly and rearwardly as seen in Fig. 2. The blade is provided with a lower inwardly curved surface l0 which tends to form a fingerlike portion II as the faces 8 and Ill merge together. The blade does not terminate in an apex, however, but is cut off to form a blunt or stub-like end I2, as seen in Fig. 2.

Attention is directed, however to the fact that this end curves inwardly and rearwardly in a claw-like configuration so that the front edge 1 negotiates a slicing action upon the face of the formation being cut. The curvature of the blades, considered one with the other, is such that the blunt edge 12 terminates quite close to the forward cutting edge of the other blade. The curvature of these blades forms a central chamber I5 into which the cuttings are washed vduring the rotation of the bit. This occurs bein which'leads off from the recess 3 in the bit.

body and may be defined by a nipple 2| of hard material. This water course 20 terminates in the blunt face l2 so as to discharge a stream of flushing fluid at high velocity from the rear edge or end of the blade. This flow of fluid will strike the forward cutting edge 1 and the face l6 so as to break up'in pieces or shavings which will be sliced off by the following blade. In this manner the highest Velocity of the flushing fluid occurs directly in front of the cutting edge and the chips or cuttings and the flushing fluid will then swirl into the chamber 15, causing suflicient agitation to break up the shavings or cuttings into fine chips. As a matter of fact the flushing fluid is scharged laterally of the well bore and will be directed upwardly to carry away the cuttings at a higher velocity than if'the discharge port were directing the fluid downwardly as in the conventional type of bit. In other words, the change in direction is only about 90 as compared with a complete reversal of 180 where the discharge is straight down. The area 23 between adjacent blades is of considerable size and may be designated as a window between the blades. This allows the escape of the swirling fluid and the broken up chips so that they may move upwardly in the well bore without choking further discharge from the bit. a

In order to further agitate the cuttings and the fluid in the chamber IS, a plurality of discharge ports 26 may also lead from the recess 3 into the upper portion ofthe chamber l5 so that a large volume of fluid will be present at this elevation to pick up the cuttings and carry them on up the well bore.

Particular attention is directed to the gentle curvature and stream lined configuration of the great because it would tend to wedge the blades to gauge by the lower portion of the blade but would be cut to its full diameter by the upper portion of the blade. In this manner the cutting action is distributed over a greater surface which results in less heating action upon the bit. The angle of inclination with respect to the Vertical would, of course, be varied but it cannot be too and the cuttings.

The vertically inclined side edge of the blade cuts or digs downwardly so that the gauge of the hole is maintained as the wear gradually creeps blades and the body so as to present no sharp surfaces against which the cuttings may impinge and cause wearer balling up of the bit.

Figs. 4, 5 and 6 show the same type of. bit which is provided with three blades, however, as

distinguished from the two blades of Figs. 1, 2,

and 3. The general arrangement, curvature and streamlining are substantially the same as those previously described. ever, that as. seen in Fig. 4, the, discharge from the lower end 22 of the passage 20 is substantially perpendicular to the front edge 18 of the following. cutting blade. In other words, the stream offluid being discharged by one blade impinges upon the cutting face of the next blade to break up thecuttings and wash them from the cutting surface.

Figs. 2 and 4 best illustrate'the gradual curva-.

ture of the cutting edge I and it will be seen that the blade negotiates a cutting action from.

its lower end entirely up to the shoulder where it merges with the body 2. This gives an exceptionally long cutting edge. The bit may however be'made up with the conventional squared corner blades if desired but it has been found that such corners wear away rather quickly and for this It should be noted, howincluding a body, a connection for the drill stem,

aplurality of blades extending from said body up the curved edge. When the bit is rotated in an inclined bore, the bit tends to straighten the bore because the weight of the bit causes a greater cutting action on the low side of the bore.

The action of the cutting edge 1 may be described as a shaving action'which occurs throughout thelength of the edge "I. In this manner the shavings can be readily broken up, and Washed out from the bit thru the windows 23. Attention is directed to the fact that these windows 23 cannot extend for too great a distance above the lower ends of the blades because if the washing action of the drilling fluid cause the cuttings to impinge against the Wall of the well bore too far below the area 23, there would be a rebound action by which the liquid would tend to reenter the opening 23 so that it has been found in practice that the distance must be correctly proportioned in order to cause the cuttings and drilling fluid to wash out of the windows and proceed upwardly around the drill collar.

In connection withthe discharge of the drilling fluid from the openings 22 against the next following blade, it seems obvious that the force or velocity of the fluid is not checked because 01 the curvature of the passages 20 and the fact that the discharge 22 is laterally of the well bore rather than having a discharge which is substantially vertical. In this manner the stream of fluid will follow a gradual curvature from the discharge port 22 against the blade and be directed upwardly across the bit to discharge from the window on the opposite side while maintaining a considerable amountof its original velocity. A distinguished from this, when the drilling fluid is directed downwardly, it loses its velocity in changing direction to reverse its movement and flow upwardly in the well bore. It has been found that with a bit of this construction, that the speed of circulation is not lost or substantialiy impaired and that a light weight bit operated at a medium speed tends to advancequite rapidly due to the auger effect of the blades.

Blades constructed in accordance with the in-. vention have proven exceptionally satisfactory in operation and while the blade-appears to be light in construction as compared with the heavier bits which have gone before, it has been found that due to the slicing action of the blades, that a hole may be drilled at a very high rate of speed.

Broadly the invention contemplates a clawlike slicing type of drag bit wherein the cuttings are broken up and'washed from the cutting area..-

each blade comprising a bowed arm curved portion having a verticallyinclined forwardly facing thin edge, a curved slicing edge merging the lower portion of the'vertically inclined edge and central axis of the bit body to provide a slicing face, and a window extending up into the body above the rear of each blade to facilitate the discharge of drilling fluid and cuttings upwardly into the well bore.

2. A slicing blade type of bit for well drilling including a body, a connection for the drill stem, a plurality of blades extending from said body each blade comprising a bowed arm curved portion having a vertically inclined forwardly facing thin edge, and a curved slicing edge merging the lower portion of the vertically inclined edge and curved downwardly and inwardly just behind the central axis of the bit body to provide a slicing face, said blade being substantially triangular in cross section, and inclined generally downward and rearwardly.

3. A slicing blade type of bit for well drilling including a body, a connection for the drill stem, a plurality of blades extending from said body each blade comprising a bowed arm curved portion having a vertically inclined forwardly facing thin edge, and a curved slicing edge merging the lower portion of the vertically inclined edge and curved downwardly and inwardly just behind the central axis of the bit body to provide a slicing face, said blade being substantially triangular in cross section and gradually reduced in size to terminate in a rearwardly facing blunt end.

4. A slicing blade type of bit for well drilling including a body, a connection for the drill stem, a plurality of blades extending from said body each blade comprising a bowed arm. portion having a substantially vertical forwardly facing thin edge, a curved slicing edge joining the lower portion of the vertical edge and curved downwardly and inwardly just behind the central axis of the bit body to provide a slicing face, said blade being substantially triangular in cross section and gradually reduced in size to terminate in a blunt end, and a water course through said blade to discharge from said end.

5. A slicing blade type of bit for well drilling including a body, a connection for the drill stem, a plurality of blades extending from said body each blade comprising a bowed arm portion having a vertical forwardly facing thin edge, a curved slicing edge joining the lower portion of the vertical edge and curved downwardly and inwardly just behind the central axis of the bit body to provide a slicing face, said blade being substantially triangular in cross section and gradually reduced in size to terminate in a blunt end, and a water course through said blade to discharge fro-m said end, said blades being symmetrically arranged so that the discharge from the end of one blade is substantially directly against the slicing face of the following blade.

6. A drill bit of the drag type comprising a body, a plurality of downwardly inwardly and rearwardly curved blades each blade having a slicing edge which extends downwardly from the body and is inclined rearwardly and rounded inwardly to a point behind the bit axis, said blades providing a central chamber with outlet windows between the adjacent rear and front edges, and means to discharge drilling fluid into such chamber from each blade to flow across the face of the following blade and pass upwardly through the opposite window.

7. A drill bit of the drag type comprising a body, a plurality of downwardly inwardly curved blades each blade having a slicing edge which extends downwardly from the body and isoinclined rearwardly and rounded inwardly to a point behind the bit axis, said blades providing a central chamber with outlets between the adjacent rear and front edges, means to discharge drilling fluid into such chamber, and additional means to discharge drilling fluid from the rear of each blade to wash the neXt following blade.

8. A drill bit of the character described including a body a plurality of blades extending downwardly therefrom, a front cutting face on each blade, a rear trailing face on each blade, and means to discharge flushing fluid from the rear of one blade onto the cutting face of the next blade.

9. A drill bit of the character described in cluding a body a plurality of blades extending downwardly therefrom, a front cutting face on each blade, a rear trailing face on each blade, and means to discharge flushing fluid from the rear of one blade onto the cutting face of the next blade, said faces being substantially perpendicular one to the other.

10. A drill bit of the character described including a body, a plurality of blades extending downwardly therefrom, a front cutting face on each blade, 2. rear trailing face on each blade, and means to discharg flushing fluid from the rear of one blade onto the cutting face of the next blade, the direction of discharge being substantially horizontal and transversely of the well bore so that the fluid tends to maintain its velocity in washing upwardly along the blades and bit.

11. A drag bit for rotary drilling including a body, a plurality of bowed arm like blades extending downwardly and having a radially inward twist so that the forward slicing edge extends downwardly, inwardly, and rearwardly of the periphery of said body, said blades defining a central open chamber like area centrally below the body, and an upwardly directed window opening between adjacent blades and leading from said chamber to facilitate the discharge of flushing fluid and cuttings from the in the well bore.

12. A drag bit for rotary drilling including a body, a plurality of bowed arm like blades extending downwardly and rearwardly of the periphery of said body, said blades defining a central open chamber like area centrally below the body, an upwardly directed window opening between adjacent blades and leading from said chamber to facilitate the discharge of flushing fluid and cuttings from. the blades upwardly in the well bore, and a flushing fluid discharge port in the inwardly turned end of each blade to discharge onto the face of the following blade.

13. A drag bit for rotary drilling including a body, a plurality of bowed arm like blades extending downwardly and rearwardly of the periphery of said body, said blades defining a central open chamber like area centrally below the body, an upwardly directed window opening between adjacent blades and leading from said chamber to facilitate the discharge of flushing fluid and cuttings from the blades upwardly in the well bore, a flushing fluid discharge port in the inwardly turned end of each blade to discharge onto the face of the following blade, and flushing fluid discharge ports from said body into the top of said chamber.

LEE R. LEISSLER.

blades upwardly 

